This invention relates to fluid sampling systems for nuclear reactor facilities, and, in particular, systems for extracting liquid and gas samples from selected locations inside nuclear reactor containments.
Nuclear reactors used for power generation are generally surrounded by a concrete or steel enclosure, or containment, that provides shielding in case of an accident that releases radioactive materials. The operating room and other support facilities are located outside the containment such that plant personnel do not normally have to enter the containment. During normal operation, during refueling and after an accident it is desirable to be able to remove samples of fluids, both liquid and gas, from various locations inside the containment to measure radiation levels and perform other types of analysis.
The fluids extracted from the containment are generally pumped through stainless steel plumbing that passes through a shielded sample room located adjacent the containment. Small samples can be removed from the sample room for remote analysis in a laboratory, and the flowing liquids and gases can be continuously monitored in the sample room by measurement instruments having remote displays in the control room. Excess fluids not removed from the sample room are then exhausted to the interior of the containment.
Because the fluids extracted from the containment can be highly radioactive, especially in a post-accident situation, the pumps traditionally used are expensive, nuclear grade active pumps. The pumps; need regular maintenance, therefore, there is redundancy included to allow continuous operation of the sampling system, adding further expense. Additionally, the pumps can themselves become activated by the radioactive materials flowing through them. This can make maintenance of the pumps difficult and hazardous to personnel, and also creates a waste disposal problem.